Determination of the water-soluble polymer poly(N-vinylcaprolactam) in wastewater effluents by continuous-flow off-line pyrolysis-GC/MS

Abstract

High production rates and wide areas of application of water-soluble polymers indicate their potential occurrence in wastewater. Poly(N-vinylcaprolactam) (PNVCL) is such a water-soluble and poorly biodegradable polymer with non-ionic, non-sticky, non-toxic and thermosensitive properties. Its field of applications covers being a constituent in aerosol sprays, pump sprays, and lotions as well as its usage as flocculant in wastewater treatment plants. However, although discharged into sewage treatment plants at high amounts, analytical methods for determining water soluble polymers, in particular PNVCL, in environmental samples are still missing. Therefore, this study aims at developing an efficient analytical method for detecting trace levels of poly(N-vinylcaprolactam) in wastewaters by applying continuous-flow off-line Py-GC/MS for the first time. The approach was based on the identification of specific off-line pyrolysis products (ε-caprolactam, N-vinylcaprolactam) that haven been used in the following for a calibration process that allowed a quantitative determination. An evaluation including specificity, linearity, sensitivity and reproducibility characterized this approach as very suitable for detection of this polymer in complex environmental matrices such as wastewaters. Finally, the transferability has been checked by analyzing a real wastewater from a sewage treatment plant effluent. Here limitations especially due to matrix effects are lowering the sensitivity of the pyrolysis-based method. Nevertheless, a contamination with approx. 70 µg/L of poly(N-vinylcaprolactam) was determined pointing to a huge emission of PNVCL into the aquatic environment and a general high environmental relevance of this synthetic polymer. Noteworthy, this is the first report on the occurrence of poly(N-vinylcaprolactam) in environmental samples.

Superabsorbent polymers in soil: The new microplastics?

“…Pyrolysis-GC/MS has already been successfully applied for the quantification of poly(N-vinyl)caprolactam in wastewater effluents at 70 μg L À1 (Vidovic et al, 2022) or PAM in sewage sludge with a limit of detection of 250 mg kg À1 (Kronimus and Schwarzbauer, 2007). Since SAPs are typically less thermally stable than other thermoplastic polymers, sample pyrolysis is conducted at temperatures below 500 °C and combined with thermally assisted hydrolysis and methylation agents like N,O-bis(trimethylsilyl) trifluoroacetamide and trimethylchlorosilane (Kumooka, 2004) or tetramethylammonium hydroxide (Kronimus and Schwarzbauer, 2007).…”

Identification of Water-Soluble Polymers through Machine Learning of Fluorescence Signals from Multiple Peptide Sensors

“…However, analytical methods for water-soluble polymers have hardly been proposed. A potential candidate is based on gas chromatography/mass spectrometry of pyrolysis products obtained from solidified samples. − However, sample preparation is laborious, and special apparatuses are needed. Therefore, simple and convenient methods are urgently needed to identify water-soluble polymers, particularly in their solution state.…”